refactor: Enhance Assembly Editor with Language Definition and Toolset Integration

- Introduced a new language definition for the 65816 assembly language, improving syntax highlighting and code editing capabilities.
- Updated the AssemblyEditor to utilize the new language definition and integrated a toolset for file management actions, enhancing user experience.
- Refactored the file handling logic to support dynamic file opening and saving, ensuring better resource management within the editor.
- Removed deprecated tab view code, transitioning to a more modular card-based layout for active files, improving UI responsiveness and organization.

src/app/editor/dungeon/dungeon_editor_v2.h

@@ -12,6 +12,7 @@
 #include "dungeon_room_loader.h"
 #include "app/zelda3/dungeon/room.h"
 #include "app/zelda3/dungeon/room_entrance.h"
+#include "app/gui/editor_layout.h"
 #include "imgui/imgui.h"
 
 namespace yaze {
@@ -79,6 +80,7 @@ class DungeonEditorV2 : public Editor {
   // Simple UI layout
   void DrawLayout();
   void DrawRoomTab(int room_id);
+  void DrawToolset();
   
   // Room selection callback
   void OnRoomSelected(int room_id);